Writing a compiler in Python using Lex, Yacc and LLVM • Hacker News Board

Re: Writing a compiler in Python using Lex, Yacc and LLVM

#41

Post by ilkhd2 » Sun, Sep 20, 2009, 7:24 PM UTC

mahmud wrote: post #35

ilkhd2 wrote: post #33

Earlier quoted context omitted.

You probably missed the point - my concern is not the speed of compilation _of_ _the_ _compiler_ _itself_ - it is totally irrelevant, what is important is the performance of _created_ _compiler_, which is going to be ok, taking into account the quality of Stalins optimizer.

We can debate the performance of a hypothetical compiler for eternity, or we can cite examples; slow compilers written in a non-C language along with publicly available input data. i.e. benchmarks or it didn't happen.

And I do not know where you saw me saying C is the ultimate language for making compilers. I never said that, I do not think so, I just said python/ruby are bad for the task.

Re: Writing a compiler in Python using Lex, Yacc and LLVM

#42

Post by ilkhd2 » Sun, Sep 20, 2009, 7:28 PM UTC

dkersten wrote: post #37

ilkhd2 wrote: post #29

Earlier quoted context omitted.

What make you think that I think this way? Linux kernel is just an example of relatively big program, where performance of the compiler is an important issue. Another example of performance-sensitive application of compilers is background Java compiler in Eclipse - even for rather small programs it has to be fast. Ruby is 10-100 (actually more than that) times slower than C/Java, So if you optimizer (wriiten in C/Jav…

Background compilers do not need to perform heavy optimiztion, so can skip a lot of time consuming steps.

Even if they do not need a lot of optimizations, they still have to be fast. You would not like the performance would they be written in ruby.

And do not forget by the way that Ruby is a memory hog.

http://shootout.alioth.debian.org/u32q/benchmark.php?test=al...

Re: Writing a compiler in Python using Lex, Yacc and LLVM

#43

Post by anamax » Sun, Sep 20, 2009, 8:17 PM UTC

ilkhd2 wrote: post #4

pmorici wrote: post #3

Earlier quoted context omitted.

Did you read the post? The guy was writing this for an academic project where speed didn't matter and secondly he was using LLVM for code generation. low level details don't really come into play in compiler construction until the code generation step most of the work up to that point is text parsing, syntax checking, and AST creation. In other words tasks suited perfectly to a language like Python.

> low level details don't really come into play in compiler construction until the code generation -- Not true. modern compilers do a lot of optimization long before code generation, and you really want to have for example floating point to be behaving exactly like in target language - if you collapse operations on constants such as 1.0D + 4.0. And aside from optimization, lexer - it has to distinguish single-precisi…

> you really want to have for example floating point to be behaving exactly like in target language

You keep writing that like it's a hard thing to do. It isn't. More to the point, it's a small part of the whole problem.

Re: Writing a compiler in Python using Lex, Yacc and LLVM

#44

Post by mahmud » Mon, Sep 21, 2009, 5:07 AM UTC

ilkhd2 wrote: post #41

mahmud wrote: post #35

Earlier quoted context omitted.

We can debate the performance of a hypothetical compiler for eternity, or we can cite examples; slow compilers written in a non-C language along with publicly available input data. i.e. benchmarks or it didn't happen.

And I do not know where you saw me saying C is the ultimate language for making compilers. I never said that, I do not think so, I just said python/ruby are bad for the task.

Sorry, I must have misunderstood your intent then. Python and Ruby are probably fast enough for compiler construction as well; I am sure they could be tweaked by an expert to yield acceptable performance, but I am just not such expert :-)